This present invention relates to improvements to an optical signal disc reading apparatus in which a disc, such as a compact disc or video disc, is loaded on a turntable and an optical pickup reads a digital signal recorded on the disc.
A conventional optical signal disc reading apparatus is shown in FIG. 1 and will now be described.
In this figure, reference numeral 1 denotes a motor, the shaft of which is fixed to a turntable 3.
Reference numeral 5 denotes a disc carriage which receives a disc 6 at a position adjacent the front face of the player. In order to set the disc on the turntable 3, the disc 6 is conveyed until the disc 6 and turntable 3 are aligned, and the disc carriage 5 then lowers the disc 6 onto the turntable 3.
Reference numeral 4 denotes a clamper which is lowered when the disc carriage 5 is lowered to push the disc 6 placed on the turntable 3 against the turntable 3.
Reference numeral 7 denotes a centering hub pushed up by spring 8 and fitted into a central hole in the disc 6 by the pushing operation of the clamper 4 to thereby center the disc 6.
Reference numeral 2 denotes an optical pickup which reads a signal from the disc 6 when the disc is set in place on the turntable and rotated by the motor 1.
The optical pickup 2 and motor 1 are disposed on the same side in the conventional optical signal disc reading apparatus. Therefore, the minimum diameter of the region of the disc 6 from which the pickup 2 can read a signal is larger than the sum of the outer dimension of the motor 1 plus a dimension in the radial direction from the objective lens of the pickup 2.
Therefore, for a disk player for discs having a small minimum signal recording diameter such as a compact disc, the shaft of the motor 1 must be elongated to allow the motor to be mounted in a lower position to provide a space between motor 1 and turntable 3 into which the pickup 2 can enter, as shown in FIG. 1. Therefore, a drawback results in that there is an unavoidable increase in the vertical dimension of the player.
The outer diameter of the motor 1 may be reduced; however, this increases the cost of the motor 1.
Also, since the turntable 3 should not contact the pickup 2 at the outer periphery thereof, the turntable 3 should be reduced in outer diameter. In such a case, if the disc 6 is warped, the warping greatly influences the signal reading process to thereby render playing the disc difficult.